//---------------------------------------------------------------------------
#include "TinyFrame.h"

#include <stdlib.h>  // - for malloc() if dynamic constructor is used
//---------------------------------------------------------------------------

// Compatibility with ESP8266 SDK
#ifdef ICACHE_FLASH_ATTR
#define _TF_FN ICACHE_FLASH_ATTR
#else
#define _TF_FN
#endif

// Helper macros
#define TF_MIN(a, b) ((a) < (b) ? (a) : (b))
#define TF_TRY(func)           \
  do {                         \
    if (!(func)) return false; \
  } while (0)

// Type-dependent masks for bit manipulation in the ID field
#define TF_ID_MASK (TF_ID)(((TF_ID)1 << (sizeof(TF_ID) * 8 - 1)) - 1)
#define TF_ID_PEERBIT (TF_ID)((TF_ID)1 << ((sizeof(TF_ID) * 8) - 1))

#if !TF_USE_MUTEX
// Not thread safe lock implementation, used if user did not provide a better
// one. This is less reliable than a real mutex, but will catch most bugs caused
// by inappropriate use fo the API.

/** Claim the TX interface before composing and sending a frame */
static bool TF_ClaimTx(TinyFrame *tf) {
  if (tf->soft_lock) {
    TF_Error("TF already locked for tx!");
    return false;
  }

  tf->soft_lock = true;
  return true;
}

/** Free the TX interface after composing and sending a frame */
static void TF_ReleaseTx(TinyFrame *tf) { tf->soft_lock = false; }
#endif

// region Checksums

#if TF_CKSUM_TYPE == TF_CKSUM_NONE

static TF_CKSUM TF_CksumStart(void) { return 0; }

static TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte) { return cksum; }

static TF_CKSUM TF_CksumEnd(TF_CKSUM cksum) { return cksum; }

#elif TF_CKSUM_TYPE == TF_CKSUM_XOR

static TF_CKSUM TF_CksumStart(void) { return 0; }

static TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte) {
  return cksum ^ byte;
}

static TF_CKSUM TF_CksumEnd(TF_CKSUM cksum) { return (TF_CKSUM)~cksum; }

#elif TF_CKSUM_TYPE == TF_CKSUM_CRC8

static inline uint8_t crc8_bits(uint8_t data) {
  uint8_t crc = 0;
  if (data & 1) crc ^= 0x5e;
  if (data & 2) crc ^= 0xbc;
  if (data & 4) crc ^= 0x61;
  if (data & 8) crc ^= 0xc2;
  if (data & 0x10) crc ^= 0x9d;
  if (data & 0x20) crc ^= 0x23;
  if (data & 0x40) crc ^= 0x46;
  if (data & 0x80) crc ^= 0x8c;
  return crc;
}

static TF_CKSUM TF_CksumStart(void) { return 0; }

static TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte) {
  return crc8_bits(byte ^ cksum);
}

static TF_CKSUM TF_CksumEnd(TF_CKSUM cksum) { return cksum; }

#elif TF_CKSUM_TYPE == TF_CKSUM_CRC16

// TODO try to replace with an algorithm
/** CRC table for the CRC-16. The poly is 0x8005 (x^16 + x^15 + x^2 + 1) */
static const uint16_t crc16_table[256] = {
    0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601,
    0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, 0xCC01, 0x0CC0,
    0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81,
    0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, 0xD801, 0x18C0, 0x1980, 0xD941,
    0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01,
    0x1DC0, 0x1C80, 0xDC41, 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0,
    0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081,
    0x1040, 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
    0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00,
    0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 0xFA01, 0x3AC0,
    0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981,
    0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 0xEE01, 0x2EC0, 0x2F80, 0xEF41,
    0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700,
    0xE7C1, 0xE681, 0x2640, 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0,
    0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281,
    0x6240, 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
    0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 0xAA01,
    0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, 0x7800, 0xB8C1,
    0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80,
    0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, 0xB401, 0x74C0, 0x7580, 0xB541,
    0x7700, 0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101,
    0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0,
    0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481,
    0x5440, 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
    0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, 0x8801,
    0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 0x4E00, 0x8EC1,
    0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400, 0x84C1, 0x8581,
    0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 0x8201, 0x42C0, 0x4380, 0x8341,
    0x4100, 0x81C1, 0x8081, 0x4040};

static TF_CKSUM TF_CksumStart(void) { return 0; }

static TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte) {
  return (cksum >> 8) ^ crc16_table[(cksum ^ byte) & 0xff];
}

static TF_CKSUM TF_CksumEnd(TF_CKSUM cksum) { return cksum; }

#elif TF_CKSUM_TYPE == TF_CKSUM_CRC32

// TODO try to replace with an algorithm
static const uint32_t crc32_table[] =
    {/* CRC polynomial 0xedb88320 */
     0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
     0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
     0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
     0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
     0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
     0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
     0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
     0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
     0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
     0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
     0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
     0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
     0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
     0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
     0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
     0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
     0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
     0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
     0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
     0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
     0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
     0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
     0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
     0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
     0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
     0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
     0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
     0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
     0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
     0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
     0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
     0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
     0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
     0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
     0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
     0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
     0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
     0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
     0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
     0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
     0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
     0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
     0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d};

static TF_CKSUM TF_CksumStart(void) { return (TF_CKSUM)0xFFFFFFFF; }

static TF_CKSUM TF_CksumAdd(TF_CKSUM cksum, uint8_t byte) {
  return crc32_table[((cksum) ^ ((uint8_t)byte)) & 0xff] ^ ((cksum) >> 8);
}

static TF_CKSUM TF_CksumEnd(TF_CKSUM cksum) { return (TF_CKSUM)~cksum; }

#endif

#define CKSUM_RESET(cksum)     \
  do {                         \
    (cksum) = TF_CksumStart(); \
  } while (0)
#define CKSUM_ADD(cksum, byte)              \
  do {                                      \
    (cksum) = TF_CksumAdd((cksum), (byte)); \
  } while (0)
#define CKSUM_FINALIZE(cksum)       \
  do {                              \
    (cksum) = TF_CksumEnd((cksum)); \
  } while (0)

// endregion

// region Init

/** Init with a user-allocated buffer */
bool _TF_FN TF_InitStatic(TinyFrame *tf, TF_Peer peer_bit) {
  if (tf == NULL) {
    TF_Error("TF_InitStatic() failed, tf is null.");
    return false;
  }

  // Zero it out, keeping user config
  uint32_t usertag = tf->usertag;
  void *userdata = tf->userdata;

  memset(tf, 0, sizeof(struct TinyFrame_));

  tf->usertag = usertag;
  tf->userdata = userdata;

  tf->peer_bit = peer_bit;
  return true;
}

/** Init with malloc */
TinyFrame *_TF_FN TF_Init(TF_Peer peer_bit) {
  TinyFrame *tf = malloc(sizeof(TinyFrame));
  if (!tf) {
    TF_Error("TF_Init() failed, out of memory.");
    return NULL;
  }

  TF_InitStatic(tf, peer_bit);
  return tf;
}

/** Release the struct */
void TF_DeInit(TinyFrame *tf) {
  if (tf == NULL) return;
  free(tf);
}

// endregion Init

// region Listeners

/** Reset ID listener's timeout to the original value */
static inline void _TF_FN renew_id_listener(struct TF_IdListener_ *lst) {
  lst->timeout = lst->timeout_max;
}

/** Notify callback about ID listener's demise & let it free any resources in
 * userdata */
static void _TF_FN cleanup_id_listener(TinyFrame *tf, TF_COUNT i,
                                       struct TF_IdListener_ *lst) {
  TF_Msg msg;
  if (lst->fn == NULL) return;

  // Make user clean up their data - only if not NULL
  if (lst->userdata != NULL || lst->userdata2 != NULL) {
    msg.userdata = lst->userdata;
    msg.userdata2 = lst->userdata2;
    msg.data = NULL;  // this is a signal that the listener should clean up
    lst->fn(tf,
            &msg);  // return value is ignored here - use TF_STAY or TF_CLOSE
  }

  lst->fn = NULL;  // Discard listener
  lst->fn_timeout = NULL;

  if (i == tf->count_id_lst - 1) {
    tf->count_id_lst--;
  }
}

/** Clean up Type listener */
static inline void _TF_FN cleanup_type_listener(TinyFrame *tf, TF_COUNT i,
                                                struct TF_TypeListener_ *lst) {
  lst->fn = NULL;  // Discard listener
  if (i == tf->count_type_lst - 1) {
    tf->count_type_lst--;
  }
}

/** Clean up Generic listener */
static inline void _TF_FN cleanup_generic_listener(
    TinyFrame *tf, TF_COUNT i, struct TF_GenericListener_ *lst) {
  lst->fn = NULL;  // Discard listener
  if (i == tf->count_generic_lst - 1) {
    tf->count_generic_lst--;
  }
}

/** Add a new ID listener. Returns 1 on success. */
bool _TF_FN TF_AddIdListener(TinyFrame *tf, TF_Msg *msg, TF_Listener cb,
                             TF_Listener_Timeout ftimeout, TF_TICKS timeout) {
  TF_COUNT i;
  struct TF_IdListener_ *lst;
  for (i = 0; i < TF_MAX_ID_LST; i++) {
    lst = &tf->id_listeners[i];
    // test for empty slot
    if (lst->fn == NULL) {
      lst->fn = cb;
      lst->fn_timeout = ftimeout;
      lst->id = msg->frame_id;
      lst->userdata = msg->userdata;
      lst->userdata2 = msg->userdata2;
      lst->timeout_max = lst->timeout = timeout;
      if (i >= tf->count_id_lst) {
        tf->count_id_lst = (TF_COUNT)(i + 1);
      }
      return true;
    }
  }

  TF_Error("Failed to add ID listener");
  return false;
}

/** Add a new Type listener. Returns 1 on success. */
bool _TF_FN TF_AddTypeListener(TinyFrame *tf, TF_TYPE frame_type,
                               TF_Listener cb) {
  TF_COUNT i;
  struct TF_TypeListener_ *lst;
  for (i = 0; i < TF_MAX_TYPE_LST; i++) {
    lst = &tf->type_listeners[i];
    // test for empty slot
    if (lst->fn == NULL) {
      lst->fn = cb;
      lst->type = frame_type;
      if (i >= tf->count_type_lst) {
        tf->count_type_lst = (TF_COUNT)(i + 1);
      }
      return true;
    }
  }

  TF_Error("Failed to add type listener");
  return false;
}

/** Add a new Generic listener. Returns 1 on success. */
bool _TF_FN TF_AddGenericListener(TinyFrame *tf, TF_Listener cb) {
  TF_COUNT i;
  struct TF_GenericListener_ *lst;
  for (i = 0; i < TF_MAX_GEN_LST; i++) {
    lst = &tf->generic_listeners[i];
    // test for empty slot
    if (lst->fn == NULL) {
      lst->fn = cb;
      if (i >= tf->count_generic_lst) {
        tf->count_generic_lst = (TF_COUNT)(i + 1);
      }
      return true;
    }
  }

  TF_Error("Failed to add generic listener");
  return false;
}

/** Remove a ID listener by its frame ID. Returns 1 on success. */
bool _TF_FN TF_RemoveIdListener(TinyFrame *tf, TF_ID frame_id) {
  TF_COUNT i;
  struct TF_IdListener_ *lst;
  for (i = 0; i < tf->count_id_lst; i++) {
    lst = &tf->id_listeners[i];
    // test if live & matching
    if (lst->fn != NULL && lst->id == frame_id) {
      cleanup_id_listener(tf, i, lst);
      return true;
    }
  }

  TF_Error("ID listener %d to remove not found", (int)frame_id);
  return false;
}

/** Remove a type listener by its type. Returns 1 on success. */
bool _TF_FN TF_RemoveTypeListener(TinyFrame *tf, TF_TYPE type) {
  TF_COUNT i;
  struct TF_TypeListener_ *lst;
  for (i = 0; i < tf->count_type_lst; i++) {
    lst = &tf->type_listeners[i];
    // test if live & matching
    if (lst->fn != NULL && lst->type == type) {
      cleanup_type_listener(tf, i, lst);
      return true;
    }
  }

  TF_Error("Type listener %d to remove not found", (int)type);
  return false;
}

/** Remove a generic listener by its function pointer. Returns 1 on success. */
bool _TF_FN TF_RemoveGenericListener(TinyFrame *tf, TF_Listener cb) {
  TF_COUNT i;
  struct TF_GenericListener_ *lst;
  for (i = 0; i < tf->count_generic_lst; i++) {
    lst = &tf->generic_listeners[i];
    // test if live & matching
    if (lst->fn == cb) {
      cleanup_generic_listener(tf, i, lst);
      return true;
    }
  }

  TF_Error("Generic listener to remove not found");
  return false;
}

/** Handle a message that was just collected & verified by the parser */
static void _TF_FN TF_HandleReceivedMessage(TinyFrame *tf) {
  TF_COUNT i;
  struct TF_IdListener_ *ilst;
  struct TF_TypeListener_ *tlst;
  struct TF_GenericListener_ *glst;
  TF_Result res;

  // Prepare message object
  TF_Msg msg;
  TF_ClearMsg(&msg);
  msg.frame_id = tf->id;
  msg.is_response = false;
  msg.type = tf->type;
  msg.data = tf->data;
  msg.len = tf->len;

  // Any listener can consume the message, or let someone else handle it.

  // The loop upper bounds are the highest currently used slot index
  // (or close to it, depending on the order of listener removals).

  // ID listeners first
  for (i = 0; i < tf->count_id_lst; i++) {
    ilst = &tf->id_listeners[i];

    if (ilst->fn && ilst->id == msg.frame_id) {
      msg.userdata = ilst->userdata;  // pass userdata pointer to the callback
      msg.userdata2 = ilst->userdata2;
      res = ilst->fn(tf, &msg);
      ilst->userdata = msg.userdata;    // put it back (may have changed the
                                        // pointer or set to NULL)
      ilst->userdata2 = msg.userdata2;  // put it back (may have changed the
                                        // pointer or set to NULL)

      if (res != TF_NEXT) {
        // if it's TF_CLOSE, we assume user already cleaned up userdata
        if (res == TF_RENEW) {
          renew_id_listener(ilst);
        } else if (res == TF_CLOSE) {
          // Set userdata to NULL to avoid calling user for cleanup
          ilst->userdata = NULL;
          ilst->userdata2 = NULL;
          cleanup_id_listener(tf, i, ilst);
        }
        return;
      }
    }
  }
  // clean up for the following listeners that don't use userdata (this avoids
  // data from an ID listener that returned TF_NEXT from leaking into Type and
  // Generic listeners)
  msg.userdata = NULL;
  msg.userdata2 = NULL;

  // Type listeners
  for (i = 0; i < tf->count_type_lst; i++) {
    tlst = &tf->type_listeners[i];

    if (tlst->fn && tlst->type == msg.type) {
      res = tlst->fn(tf, &msg);

      if (res != TF_NEXT) {
        // type listeners don't have userdata.
        // TF_RENEW doesn't make sense here because type listeners don't expire
        // = same as TF_STAY

        if (res == TF_CLOSE) {
          cleanup_type_listener(tf, i, tlst);
        }
        return;
      }
    }
  }

  // Generic listeners
  for (i = 0; i < tf->count_generic_lst; i++) {
    glst = &tf->generic_listeners[i];

    if (glst->fn) {
      res = glst->fn(tf, &msg);

      if (res != TF_NEXT) {
        // generic listeners don't have userdata.
        // TF_RENEW doesn't make sense here because generic listeners don't
        // expire = same as TF_STAY

        // note: It's not expected that user will have multiple generic
        // listeners, or ever actually remove them. They're most useful as
        // default callbacks if no other listener handled the message.

        if (res == TF_CLOSE) {
          cleanup_generic_listener(tf, i, glst);
        }
        return;
      }
    }
  }

  TF_Error("Unhandled message, type %d", (int)msg.type);
}

/** Externally renew an ID listener */
bool _TF_FN TF_RenewIdListener(TinyFrame *tf, TF_ID id) {
  TF_COUNT i;
  struct TF_IdListener_ *lst;
  for (i = 0; i < tf->count_id_lst; i++) {
    lst = &tf->id_listeners[i];
    // test if live & matching
    if (lst->fn != NULL && lst->id == id) {
      renew_id_listener(lst);
      return true;
    }
  }

  TF_Error("Renew listener: not found (id %d)", (int)id);
  return false;
}

// endregion Listeners

// region Parser

/** Handle a received byte buffer */
void _TF_FN TF_Accept(TinyFrame *tf, const uint8_t *buffer, uint32_t count) {
  uint32_t i;
  for (i = 0; i < count; i++) {
    TF_AcceptChar(tf, buffer[i]);
  }
}

/** Reset the parser's internal state. */
void _TF_FN TF_ResetParser(TinyFrame *tf) {
  tf->state = TFState_SOF;
  // more init will be done by the parser when the first byte is received
}

/** SOF was received - prepare for the frame */
static void _TF_FN pars_begin_frame(TinyFrame *tf) {
  // Reset state vars
  CKSUM_RESET(tf->cksum);
#if TF_USE_SOF_BYTE
  CKSUM_ADD(tf->cksum, TF_SOF_BYTE);
#endif

  tf->discard_data = false;

  // Enter ID state
  tf->state = TFState_ID;
  tf->rxi = 0;
}

/** Handle a received char - here's the main state machine */
void _TF_FN TF_AcceptChar(TinyFrame *tf, unsigned char c) {
  // Parser timeout - clear
  if (tf->parser_timeout_ticks >= TF_PARSER_TIMEOUT_TICKS) {
    if (tf->state != TFState_SOF) {
      TF_ResetParser(tf);
      TF_Error("Parser timeout");
    }
  }
  tf->parser_timeout_ticks = 0;

// DRY snippet - collect multi-byte number from the input stream, byte by byte
// This is a little dirty, but makes the code easier to read. It's used like
// e.g. if(), the body is run only after the entire number (of data type 'type')
// was received and stored to 'dest'
#define COLLECT_NUMBER(dest, type)  \
  dest = (type)(((dest) << 8) | c); \
  if (++tf->rxi == sizeof(type))

#if !TF_USE_SOF_BYTE
  if (tf->state == TFState_SOF) {
    pars_begin_frame(tf);
  }
#endif

  //@formatter:off
  switch (tf->state) {
    case TFState_SOF:
      if (c == TF_SOF_BYTE) {
        pars_begin_frame(tf);
      }
      break;

    case TFState_ID:
      CKSUM_ADD(tf->cksum, c);
      COLLECT_NUMBER(tf->id, TF_ID) {
        // Enter LEN state
        tf->state = TFState_LEN;
        tf->rxi = 0;
      }
      break;

    case TFState_LEN:
      CKSUM_ADD(tf->cksum, c);
      COLLECT_NUMBER(tf->len, TF_LEN) {
        // Enter TYPE state
        tf->state = TFState_TYPE;
        tf->rxi = 0;
      }
      break;

    case TFState_TYPE:
      CKSUM_ADD(tf->cksum, c);
      COLLECT_NUMBER(tf->type, TF_TYPE) {
#if TF_CKSUM_TYPE == TF_CKSUM_NONE
        tf->state = TFState_DATA;
        tf->rxi = 0;
#else
        // enter HEAD_CKSUM state
        tf->state = TFState_HEAD_CKSUM;
        tf->rxi = 0;
        tf->ref_cksum = 0;
#endif
      }
      break;

    case TFState_HEAD_CKSUM:
      COLLECT_NUMBER(tf->ref_cksum, TF_CKSUM) {
        // Check the header checksum against the computed value
        CKSUM_FINALIZE(tf->cksum);

        if (tf->cksum != tf->ref_cksum) {
          TF_Error("Rx head cksum mismatch");
          TF_ResetParser(tf);
          break;
        }

        if (tf->len == 0) {
          // if the message has no body, we're done.
          TF_HandleReceivedMessage(tf);
          TF_ResetParser(tf);
          break;
        }

        // Enter DATA state
        tf->state = TFState_DATA;
        tf->rxi = 0;

        CKSUM_RESET(tf->cksum);  // Start collecting the payload

        if (tf->len > TF_MAX_PAYLOAD_RX) {
          TF_Error("Rx payload too long: %d", (int)tf->len);
          // ERROR - frame too long. Consume, but do not store.
          tf->discard_data = true;
        }
      }
      break;

    case TFState_DATA:
      if (tf->discard_data) {
        tf->rxi++;
      } else {
        CKSUM_ADD(tf->cksum, c);
        tf->data[tf->rxi++] = c;
      }

      if (tf->rxi == tf->len) {
#if TF_CKSUM_TYPE == TF_CKSUM_NONE
        // All done
        TF_HandleReceivedMessage(tf);
        TF_ResetParser(tf);
#else
        // Enter DATA_CKSUM state
        tf->state = TFState_DATA_CKSUM;
        tf->rxi = 0;
        tf->ref_cksum = 0;
#endif
      }
      break;

    case TFState_DATA_CKSUM:
      COLLECT_NUMBER(tf->ref_cksum, TF_CKSUM) {
        // Check the header checksum against the computed value
        CKSUM_FINALIZE(tf->cksum);
        if (!tf->discard_data) {
          if (tf->cksum == tf->ref_cksum) {
            TF_HandleReceivedMessage(tf);
          } else {
            TF_Error("Body cksum mismatch");
          }
        }

        TF_ResetParser(tf);
      }
      break;
  }
  //@formatter:on
}

// endregion Parser

// region Compose and send

// Helper macros for the Compose functions
// use variables: si - signed int, b - byte, outbuff - target buffer, pos -
// count of bytes in buffer

/**
 * Write a number to the output buffer.
 *
 * @param type - data type
 * @param num - number to write
 * @param xtra - extra callback run after each byte, 'b' now contains the byte.
 */
#define WRITENUM_BASE(type, num, xtra)         \
  for (si = sizeof(type) - 1; si >= 0; si--) { \
    b = (uint8_t)((num) >> (si * 8) & 0xFF);   \
    outbuff[pos++] = b;                        \
    xtra;                                      \
  }

/**
 * Do nothing
 */
#define _NOOP()

/**
 * Write a number without adding its bytes to the checksum
 *
 * @param type - data type
 * @param num - number to write
 */
#define WRITENUM(type, num) WRITENUM_BASE(type, num, _NOOP())

/**
 * Write a number AND add its bytes to the checksum
 *
 * @param type - data type
 * @param num - number to write
 */
#define WRITENUM_CKSUM(type, num) WRITENUM_BASE(type, num, CKSUM_ADD(cksum, b))

/**
 * Compose a frame (used internally by TF_Send and TF_Respond).
 * The frame can be sent using TF_WriteImpl(), or received by TF_Accept()
 *
 * @param outbuff - buffer to store the result in
 * @param msg - message written to the buffer
 * @return nr of bytes in outbuff used by the frame, 0 on failure
 */
static inline uint32_t _TF_FN TF_ComposeHead(TinyFrame *tf, uint8_t *outbuff,
                                             TF_Msg *msg) {
  int8_t si = 0;  // signed small int
  uint8_t b = 0;
  TF_ID id = 0;
  TF_CKSUM cksum = 0;
  uint32_t pos = 0;

  (void)cksum;  // suppress "unused" warning if checksums are disabled

  CKSUM_RESET(cksum);

  // Gen ID
  if (msg->is_response) {
    id = msg->frame_id;
  } else {
    id = (TF_ID)(tf->next_id++ & TF_ID_MASK);
    if (tf->peer_bit) {
      id |= TF_ID_PEERBIT;
    }
  }

  msg->frame_id =
      id;  // put the resolved ID into the message object for later use

  // --- Start ---
  CKSUM_RESET(cksum);

#if TF_USE_SOF_BYTE
  outbuff[pos++] = TF_SOF_BYTE;
  CKSUM_ADD(cksum, TF_SOF_BYTE);
#endif

  WRITENUM_CKSUM(TF_ID, id);
  WRITENUM_CKSUM(TF_LEN, msg->len);
  WRITENUM_CKSUM(TF_TYPE, msg->type);

#if TF_CKSUM_TYPE != TF_CKSUM_NONE
  CKSUM_FINALIZE(cksum);
  WRITENUM(TF_CKSUM, cksum);
#endif

  return pos;
}

/**
 * Compose a frame (used internally by TF_Send and TF_Respond).
 * The frame can be sent using TF_WriteImpl(), or received by TF_Accept()
 *
 * @param outbuff - buffer to store the result in
 * @param data - data buffer
 * @param data_len - data buffer len
 * @param cksum - checksum variable, used for all calls to TF_ComposeBody. Must
 * be reset before first use! (CKSUM_RESET(cksum);)
 * @return nr of bytes in outbuff used
 */
static inline uint32_t _TF_FN TF_ComposeBody(uint8_t *outbuff,
                                             const uint8_t *data,
                                             TF_LEN data_len, TF_CKSUM *cksum) {
  TF_LEN i = 0;
  uint8_t b = 0;
  uint32_t pos = 0;

  for (i = 0; i < data_len; i++) {
    b = data[i];
    outbuff[pos++] = b;
    CKSUM_ADD(*cksum, b);
  }

  return pos;
}

/**
 * Finalize a frame
 *
 * @param outbuff - buffer to store the result in
 * @param cksum - checksum variable used for the body
 * @return nr of bytes in outbuff used
 */
static inline uint32_t _TF_FN TF_ComposeTail(uint8_t *outbuff,
                                             TF_CKSUM *cksum) {
  int8_t si = 0;  // signed small int
  uint8_t b = 0;
  uint32_t pos = 0;

#if TF_CKSUM_TYPE != TF_CKSUM_NONE
  CKSUM_FINALIZE(*cksum);
  WRITENUM(TF_CKSUM, *cksum);
#endif
  return pos;
}

/**
 * Begin building and sending a frame
 *
 * @param tf - instance
 * @param msg - message to send
 * @param listener - response listener or NULL
 * @param ftimeout - time out callback
 * @param timeout - listener timeout ticks, 0 = indefinite
 * @return success (mutex claimed and listener added, if any)
 */
static bool _TF_FN TF_SendFrame_Begin(TinyFrame *tf, TF_Msg *msg,
                                      TF_Listener listener,
                                      TF_Listener_Timeout ftimeout,
                                      TF_TICKS timeout) {
  TF_TRY(TF_ClaimTx(tf));

  tf->tx_pos = (uint32_t)TF_ComposeHead(
      tf, tf->sendbuf,
      msg);  // frame ID is incremented here if it's not a response
  tf->tx_len = msg->len;

  if (listener) {
    if (!TF_AddIdListener(tf, msg, listener, ftimeout, timeout)) {
      TF_ReleaseTx(tf);
      return false;
    }
  }

  CKSUM_RESET(tf->tx_cksum);
  return true;
}

/**
 * Build and send a part (or all) of a frame body.
 * Caution: this does not check the total length against the length specified in
 * the frame head
 *
 * @param tf - instance
 * @param buff - bytes to write
 * @param length - count
 */
static void _TF_FN TF_SendFrame_Chunk(TinyFrame *tf, const uint8_t *buff,
                                      uint32_t length) {
  uint32_t remain;
  uint32_t chunk;
  uint32_t sent = 0;

  remain = length;
  while (remain > 0) {
    // Write what can fit in the tx buffer
    chunk = TF_MIN(TF_SENDBUF_LEN - tf->tx_pos, remain);
    tf->tx_pos += TF_ComposeBody(tf->sendbuf + tf->tx_pos, buff + sent,
                                 (TF_LEN)chunk, &tf->tx_cksum);
    remain -= chunk;
    sent += chunk;

    // Flush if the buffer is full
    if (tf->tx_pos == TF_SENDBUF_LEN) {
      TF_WriteImpl(tf, (const uint8_t *)tf->sendbuf, tf->tx_pos);
      tf->tx_pos = 0;
    }
  }
}

/**
 * End a multi-part frame. This sends the checksum and releases mutex.
 *
 * @param tf - instance
 */
static void _TF_FN TF_SendFrame_End(TinyFrame *tf) {
  // Checksum only if message had a body
  if (tf->tx_len > 0) {
    // Flush if checksum wouldn't fit in the buffer
    if (TF_SENDBUF_LEN - tf->tx_pos < sizeof(TF_CKSUM)) {
      TF_WriteImpl(tf, (const uint8_t *)tf->sendbuf, tf->tx_pos);
      tf->tx_pos = 0;
    }

    // Add checksum, flush what remains to be sent
    tf->tx_pos += TF_ComposeTail(tf->sendbuf + tf->tx_pos, &tf->tx_cksum);
  }

  TF_WriteImpl(tf, (const uint8_t *)tf->sendbuf, tf->tx_pos);
  TF_ReleaseTx(tf);
}

/**
 * Send a message
 *
 * @param tf - instance
 * @param msg - message object
 * @param listener - ID listener, or NULL
 * @param ftimeout - time out callback
 * @param timeout - listener timeout, 0 is none
 * @return true if sent
 */
static bool _TF_FN TF_SendFrame(TinyFrame *tf, TF_Msg *msg,
                                TF_Listener listener,
                                TF_Listener_Timeout ftimeout,
                                TF_TICKS timeout) {
  TF_TRY(TF_SendFrame_Begin(tf, msg, listener, ftimeout, timeout));
  if (msg->len == 0 || msg->data != NULL) {
    // Send the payload and checksum only if we're not starting a multi-part
    // frame. A multi-part frame is identified by passing NULL to the data field
    // and setting the length. User then needs to call those functions manually
    TF_SendFrame_Chunk(tf, msg->data, msg->len);
    TF_SendFrame_End(tf);
  }
  return true;
}

// endregion Compose and send

// region Sending API funcs

/** send without listener */
bool _TF_FN TF_Send(TinyFrame *tf, TF_Msg *msg) {
  return TF_SendFrame(tf, msg, NULL, NULL, 0);
}

/** send without listener and struct */
bool _TF_FN TF_SendSimple(TinyFrame *tf, TF_TYPE type, const uint8_t *data,
                          TF_LEN len) {
  TF_Msg msg;
  TF_ClearMsg(&msg);
  msg.type = type;
  msg.data = data;
  msg.len = len;
  return TF_Send(tf, &msg);
}

/** send with a listener waiting for a reply, without the struct */
bool _TF_FN TF_QuerySimple(TinyFrame *tf, TF_TYPE type, const uint8_t *data,
                           TF_LEN len, TF_Listener listener,
                           TF_Listener_Timeout ftimeout, TF_TICKS timeout) {
  TF_Msg msg;
  TF_ClearMsg(&msg);
  msg.type = type;
  msg.data = data;
  msg.len = len;
  return TF_SendFrame(tf, &msg, listener, ftimeout, timeout);
}

/** send with a listener waiting for a reply */
bool _TF_FN TF_Query(TinyFrame *tf, TF_Msg *msg, TF_Listener listener,
                     TF_Listener_Timeout ftimeout, TF_TICKS timeout) {
  return TF_SendFrame(tf, msg, listener, ftimeout, timeout);
}

/** Like TF_Send, but with explicit frame ID (set inside the msg object), use
 * for responses */
bool _TF_FN TF_Respond(TinyFrame *tf, TF_Msg *msg) {
  msg->is_response = true;
  return TF_Send(tf, msg);
}

// endregion Sending API funcs

// region Sending API funcs - multipart

bool _TF_FN TF_Send_Multipart(TinyFrame *tf, TF_Msg *msg) {
  msg->data = NULL;
  return TF_Send(tf, msg);
}

bool _TF_FN TF_SendSimple_Multipart(TinyFrame *tf, TF_TYPE type, TF_LEN len) {
  return TF_SendSimple(tf, type, NULL, len);
}

bool _TF_FN TF_QuerySimple_Multipart(TinyFrame *tf, TF_TYPE type, TF_LEN len,
                                     TF_Listener listener,
                                     TF_Listener_Timeout ftimeout,
                                     TF_TICKS timeout) {
  return TF_QuerySimple(tf, type, NULL, len, listener, ftimeout, timeout);
}

bool _TF_FN TF_Query_Multipart(TinyFrame *tf, TF_Msg *msg, TF_Listener listener,
                               TF_Listener_Timeout ftimeout, TF_TICKS timeout) {
  msg->data = NULL;
  return TF_Query(tf, msg, listener, ftimeout, timeout);
}

void _TF_FN TF_Respond_Multipart(TinyFrame *tf, TF_Msg *msg) {
  msg->data = NULL;
  TF_Respond(tf, msg);
}

void _TF_FN TF_Multipart_Payload(TinyFrame *tf, const uint8_t *buff,
                                 uint32_t length) {
  TF_SendFrame_Chunk(tf, buff, length);
}

void _TF_FN TF_Multipart_Close(TinyFrame *tf) { TF_SendFrame_End(tf); }

// endregion Sending API funcs - multipart

/** Timebase hook - for timeouts */
void _TF_FN TF_Tick(TinyFrame *tf) {
  TF_COUNT i;
  struct TF_IdListener_ *lst;

  // increment parser timeout (timeout is handled when receiving next byte)
  if (tf->parser_timeout_ticks < TF_PARSER_TIMEOUT_TICKS) {
    tf->parser_timeout_ticks++;
  }

  // decrement and expire ID listeners
  for (i = 0; i < tf->count_id_lst; i++) {
    lst = &tf->id_listeners[i];
    if (!lst->fn || lst->timeout == 0) continue;
    // count down...
    if (--lst->timeout == 0) {
      TF_Error("ID listener %d has expired", (int)lst->id);
      if (lst->fn_timeout != NULL) {
        lst->fn_timeout(tf);  // execute timeout function
      }
      // Listener has expired
      cleanup_id_listener(tf, i, lst);
    }
  }
}
